Strong Foam Baffle

Smart Baffle rigid insulation is made from 4-mm-thick corrugated plastic. It comes in versions for 16-inch and 24-inch framing and is shipped as a flat panel with bendable flanges that are stapled to the rafters or trusses. According to the company, the product can support spray-foam expanding insulation without buckling, and can be installed before or after the roof sheathing. A 3-foot-long piece costs about $4 for the 16-inch version and $5.25 for the 24-inch version.